Flow sensor devices and systems

ABSTRACT

A flow rate assembly can include a housing having a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, an outer cup portion positioned at least partly within the housing, and a transducer positioned within the outer cup portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 15/713,440, filed Sep. 22, 2017, titled FLOW SENSOR DEVICES AND SYSTEMS, which claims the benefit under 35 U.S.C. 119(e) to U.S. Provisional App. No. 62/399,216, filed Sep. 23, 2016, titled FLOW SENSOR DEVICES AND SYSTEMS. The entire contents of the above-identified patent applications are incorporated by reference herein and made a part of this specification. Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with eh present application are hereby incorporated by reference under 37 CFR 1.57.

TECHNICAL FIELD

Certain embodiments discussed herein relate to devices and systems for measuring flow rate of fluid through pipes.

DISCUSSION OF THE RELATED ART

Many varieties of ultrasonic transducer assemblies exist, employing a variety of techniques and mechanisms for installing the transducer assemblies on a fluid conduit. However, such devices and certain components thereof have various limitations and disadvantages.

SUMMARY OF THE INVENTIONS

Traditionally, clamp-on transducers have been favored by ultrasonic flow meter manufacturers due to their one-size-fits-all transducer design that simplifies manufacturing and minimizes inventory. Clamp-on transducer type flow meters may be preferred because they have no moving parts, no wetted materials, and do not require a system shut-down for installation.

However, traditional clamp-on transducers require multiple installation details in order to operate correctly, such as: pipe material, pipe wall thickness, pipe inside diameter, pipe liner (if any), and fluid type. Furthermore, additional installation details are often difficult to obtain and detect, such as: the smoothness of the outer pipe wall, the smoothness of the inner pipe wall (defects in surface), and the eccentricity of the pipe (which may not be zero). The inner wall smoothness and eccentricity of the pipe are difficult to determine in the field and can drastically affect the accuracy of clamp-on ultrasonic flow meters.

Clamp-on transducers require a silicon grease (or similar substance) between the outer pipe wall and the bottom of the transducer to fill and eliminate any air gaps. This grease needs to be replaced periodically, especially in outdoor or dry locations, leading to increased maintenance requirements.

Due to the number of installation details needed for a successful installation of clamp-on ultrasonic transducers, successful installation may not occur in every situation. Additionally, clamp-on transducers are susceptible to being unintentionally moved by external forces, such as a passers-by knocking or hitting transducers by mistake. Any shift in the clamp-on transducer can jeopardize the flow measurement accuracy.

Installing clamp-on transducers can often frustrate an installer that is new to this type of technology. Even for those familiar with the process, properly addressing the plumbing details required for installation can be difficult, resulting in prolonged installation time periods.

While in-line transducers have also been developed, they suffer from performance challenges.

According to some variants, a flow rate assembly includes a housing having a housing axis, a first end having an inlet positioned along the housing axis, a second end having an outlet positioned along the housing axis, and/or a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis. In some embodiments, the assembly includes an outer cup portion positioned at least partly within the housing. The outer cup portion can include a head portion connected to a wall of the housing, an elongate portion connected to the head portion, the elongate portion having a first face facing the measurement channel, and/or at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. The assembly can include a transducer positioned within the elongate portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel. In some embodiments, a ratio of a distance between the first face of the elongate portion and the measurement channel, as measured parallel to the housing axis, to the width of the transducer is less than 4:5. In some embodiments, the first and second ends of the housing are configured to mate with open pipe end in an in-line manner.

In some embodiments, the assembly includes a second outer cup portion positioned at least partially within the housing. The second outer cup portion can include an outer head portion connected to a wall of the housing, an elongate portion connected to the head portion, and/or at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. In some embodiments, the assembly includes a second transducer positioned within the elongate portion of the second outer cup portion and sealed from fluid flow past the second outer cup portion, the second transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel. In some embodiments, the second transducer is configured generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel toward the first transducer.

In some embodiments, the outer cup portion comprises at least one boundary wall extending between the head portion and the elongate portion and forming a boundary of the at least one flow channel, wherein the at least one boundary wall is configured to straighten flow through the at least one flow channel.

In some embodiments, the outer cup portion includes an outlet channel extending between an interior of the elongate portion and an exterior of the elongate portion.

In some embodiments, the outlet channel extends through the at least one boundary wall.

In some embodiments, the housing comprises a first housing portion, a second housing portion, and third housing portion positioned between the first and second housing portions, wherein the measurement channel extends through the third housing portion.

In some embodiments, one or more electrical components are positioned within a space between the third housing portion and the first housing portion.

According to some variants, a flow rate assembly can include a housing having a housing axis, a first end having an inlet positioned along the housing axis, a second end having an outlet positioned along the housing axis, a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis, and/or a first housing chamber between the measurement channel and the inlet, as measured along the housing axis, the first housing chamber having a tapered inner wall. The assembly can include an outer cup portion positioned at least partly within the first housing chamber. The outer cup portion can include a head portion connected to a wall of the housing, an elongate portion connected to the head portion, the elongate portion having a tapered portion between the first face and the inlet and the measurement channel, and/or at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. The assembly can include a transducer positioned within the elongate portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel. In some embodiments, the tapered inner wall of the first housing chamber is substantially the same shape as the tapered portion of the elongate portion of the outer cup portion.

In some embodiments, the outer cup portion is spin welded to the housing.

In some embodiments, the assembly includes a cap positioned at the first end of the housing and forming the inlet, wherein the cap is configured to engage with an open fluid conduit.

In some embodiments, the cap is spin welded to the outer cup portion.

In some embodiments, the transducer is fluidly isolated from fluid flowing through the assembly.

In some embodiments, the assembly includes an inner cup portion positioned at least partially within the elongate portion of the outer cup portion, wherein the transducer is positioned within the inner cup portion and wherein a connection between the inner cup portion and the outer cup portion forms a seal to inhibit or prevent fluid ingress into the elongate portion of the outer cup portion.

In some embodiments, the inner cup portion has a flat face facing the measurement channel.

According to some variants, a flow rate assembly includes a housing having a housing axis, a first end having an inlet positioned along the housing axis, a second end having an outlet positioned along the housing axis, and/or a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis. The assembly can include an outer cup portion positioned at least partly within the housing, the outer cup portion including a head portion connected to a wall of the housing, an elongate portion connected to the head portion, the elongate portion having a first face facing the measurement channel, and at least one flow channel through the head portion configured to permit fluid to flow past the outer cup portion through the at least one flow channel. The assembly can include a transducer positioned within the elongate portion and sealed from fluid flow past the outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel. In some embodiments, a ratio of a distance between the first face of the elongate portion and the measurement channel, as measured parallel to the housing axis, and the width of the measurement channel is less than 1:1.

In some embodiments, the housing comprises a first housing, a second housing, and a third housing positioned between the first and second housings, wherein the flow rate assembly includes at least one fastener that extends at least partially through each of the first, second, and third housings to connect the first, second, and third housings to each other.

In some embodiments, the flow rate assembly is configured to precisely and accurately measure flow rates through the measurement channel as low as 10 mL/min.

In some embodiments, the flow rate assembly is configured to precisely and accurately measure flow rates through the measurement channel as low as 5 mL/min.

In some embodiments, the width of the measurement channel is approximately 0.25 inches.

BRIEF DESCRIPTION OF THE DRAWINGS

The present inventions are described with reference to the accompanying drawings, in which like reference characters reference like elements, and wherein:

FIG. 1 is a perspective view of a flow meter assembly.

FIG. 2 is a top elevational view of the flow meter assembly of FIG. 1 .

FIG. 3 is a left side elevational view of the flow meter assembly of FIG. 1 .

FIG. 4 is a longitudinal cross-section view of the flow meter assembly of FIG. 1 , taken along the cut-plane 4-4 of FIG. 3 .

FIG. 5 is a longitudinal cross-section view of the flow meter assembly of FIG. 1 , taken along the cut-plane 5-5 of FIG. 3 .

FIG. 6 is an exploded perspective view of the flow meter assembly of FIG. 1 .

FIG. 7 is a perspective view of a sensor assembly of the flow meter assembly of FIG. 1 .

FIG. 8 is a side elevational view of the sensor assembly of FIG. 7 .

FIG. 9 is an exploded back side perspective view of the sensor assembly of FIG. 7 .

FIG. 10 is an exploded front side perspective view of the sensor assembly of FIG. 7 .

FIG. 11 is a longitudinal cross-section view of the sensor assembly of FIG. 7 , taken along the cut-plane C-C of FIG. 8 .

FIG. 12 is a longitudinal cross-section view of a meter housing of the flow meter assembly of FIG. 1 , taken along the cut-plane 5-5 of FIG. 3 .

FIG. 13 is a top plan view of another embodiment of a flow meter assembly.

FIG. 14 is a rear plan view of the flow meter assembly of FIG. 13 .

FIG. 15 is a right-side plan view of the flow meter assembly of FIG. 13 .

FIG. 16 is a perspective exploded view of the flow meter assembly of FIG. 13 .

FIG. 17 is a longitudinal cross-section view of the flow meter assembly of FIG. 13 , taken along the cut-plane 17-17 of FIG. 15 .

FIG. 18 is a longitudinal cross-section view of the flow meter assembly of FIG. 13 , taken along the cut-plane 18-18 of FIG. 15 .

FIG. 19 is a perspective view of an outer cup portion of the flow meter assembly of FIG. 13 .

FIG. 20 is an end plan view of the outer cup portion of FIG. 19 .

FIG. 21 is a cross-section view of the outer cup portion of FIG. 19 , taken along the cut-plane 21-21 of FIG. 20 .

DETAILED DESCRIPTION OF THE INVENTIONS

While the present description sets forth specific details of various embodiments, it will be appreciated that the description is illustrative only and should not be construed in any way as limiting. Furthermore, various applications of such embodiments and modifications thereto, which may occur to those who are skilled in the art, are also encompassed by the general concepts described herein.

Ultrasonic transducer assemblies are used to measure flow characteristics of fluid flowing through pipes or other fluid lines. The transducer assemblies can include two or more transducers configured to send and receive ultrasonic signals through the fluid line and corresponding fluid. Transducer assemblies can indicate such parameters as the velocity of the fluid through the fluid line. Transducer assemblies can be used in conjunction with pumps and other devices to monitor and/or control flow rates through fluid lines.

The transducers used in traditional transducer assemblies often must be precisely aligned with the longitudinal axis of the fluid line on which they are installed. Misalignment of the transducers can increase the likelihood that the ultrasonic signals sent from the first transducer will not be received by the second transducer. Further, many transducer assemblies rely on reflection of the ultrasonic signals off of the interior surface of the pipe. Thus, the assemblies must be carefully calibrated to account for the pipe characteristics (e.g., size, material, etc.) as well as the fluid characteristics (e.g., composition, temperature, etc.).

Inline type ultrasonic flow meters can reduce installation time and improve flow measurement accuracy since several difficult to determine variables necessary for a successful installation may be removed. Inline flow meters having axially-aligned transducers can reduce or eliminate the need to reflect signals off of the interior walls of the pipe. As such, the transducers may not need to be realigned when used with different fluid types.

Furthermore, some embodiments of an inline flow meter can reduce inventory holding cost. Since the annular diameter of the flow passage of the inline flow meter can be controlled at the time of manufacture, several models with varying annular diameters can be made. External pipes of varying diameters may be connected to each model of the inline flow meter. Therefore, in some embodiments, an inline flow meter having a given diameter may be used with a range of pipe diameters. This reduces the amount of inventory required while also improving the measuring accuracy, due to the other variables, identified above, that may be controlled during manufacture of the flow meter.

An embodiment of a flow meter assembly 10 is illustrated in FIG. 1 . The flow meter assembly 10 has a first end 14 and a second end 18. The ends 14, 18 of the sensor assembly 10 can be configured to connect in-line with a pipe (not shown). In some embodiments, each of the first and second ends 14, 18 are similar or identical in structure.

The flow meter assembly 10 can include a central portion 20. The central portion 20 can extend between the first and second ends 14, 18. In some embodiments, the first and second ends 14, 18 comprise respective caps 22 a and 22 b. The central portion 20 can comprise a housing 26. The housing 26 can include a housing axis 27. The housing axis 27 can extend along a length of the housing 26 and through the first and second ends 14, 18 of the flow meter assembly 10. In some embodiments, the housing axis 27 is parallel to the length of the housing 26. One or more sensors, transducer, and/or other components can be positioned within the housing 26 and/or within the caps 22 a, 22 b. The caps 22 a, 22 b can be constructed separate from the housing 26 and can be connected to opposite ends of the housing 26 during assembly. In some embodiments, the caps 22 a, 22 b are removable from the housing 26 after assembly.

As illustrated in FIG. 2 , each of the caps 22 a, 22 b can include first mating portion 28 a, 28 b. The first mating portions 28 a, 28 b can be configured to couple with a pipe in an in-line manner. For example, the first mating portions 28 a, 28 b can each be configured to be inserted into an end of a pipe. Fasteners, welding, adhesives, and/or other connection methods/structures can be used to connect the caps 22 a, 22 b (e.g., the first mating portions 28 a, 28 b) to the pipe ends. The caps 22 a, 22 b can include apertures 32 a, 32 b (FIG. 4 ) configured to facilitate fluid flow from the pipes through the housing 26.

As illustrated in FIGS. 2-3 , the caps 22 a, 22 b can include second portions 30 a, 30 b. The second portions 30 a, 30 b have a diameter D1 greater than the diameter D2 of the first mating portions 28 a, 28 b. The second portions 30 a, 30 b can be configured to inhibit or prevent over-insertion of the caps 22 a, 22 b into the pipes and/or into the housing 26. For example, the second portions 30 a, 30 b can be sized to abut the ends of the pipes and the ends of the housing 26. The first mating portions 28 a, 28 b can extend from the second portions 30 a, 30 b.

Referring to FIG. 4 , the caps 22 a, 22 b can include third portions 34 a, 34 b. The third portions 34 a, 34 b can be connected to the second portions 30 a, 30 b and extend in a direction opposite the first mating portions 28 a, 28 b. The third portions 34 a, 34 b can have outer diameters that are sized to fit at least partially within the housing 26. For example, the third portions 34 a, 34 b can be inserted into the housing 26 when the caps 22 a, 22 b are mated with the housing 26. The inner diameter D3 of the third portions 34 a, 34 b can greater than the inner diameter D4 of the apertures 32 a, 32 b. As illustrated, the inner diameter D3 of the third portions 34 a, 34 b forms cap chambers 36 a, 36 b. The cap chamber 36 a is in fluid communication with the aperture 32 a in the cap 22 a and the cap chamber 36 b is in fluid communication with the aperture 32 b in the opposite cap 22 b.

The housing 26 can include one or more housing chambers 38 a, 38 b. For example, the inner diameter D5 of the housing 26 near the first and second ends 14, 18 of the assembly can define the housing chambers 38 a, 38 b. The housing chambers 38 a, 38 b. The inner diameter D5 can be greater than the inner diameter D4 of the apertures 32 a, 32 b. In some embodiments, the inner diameter D5 defining the housing chambers 38 a, 38 b can be within ±15%, within ±12%, within ±9%, and/or within ±5% of the inner diameter D3 of the third portions 34 a, 34 b of the caps 22 a, 22 b.

The housing 26 can include a measurement channel 40. The measurement channel 40 can extend along the housing axis 27 (FIG. 5 ). In some embodiments, the measurement channel 40 is straight and parallel to the housing axis 27. The measurement channel 40 can have a diameter D6. As illustrated, the measurement channel 40 can have a constant diameter along its length. The diameter D6 of the measurement channel 40 can be less than one or both of the diameters D4, D5 of the cap chambers. In some embodiments, the diameter D6 of the measurement channel 40 is less than ½, less than ⅓, less than ¼, and/or less than ⅕ of the diameter D5 of the housing chambers 38 a, 38 b. In some applications, the diameter D6 of the measurement channel is less than or equal to 1 inch, less than or equal to 0.75 inches, less than or equal to 0.5 inches, and/or less than or equal to 0.25 inches. For example, the diameter D6 of the measurement channel 40 can be approximately 0.25 inches.

As illustrated in FIGS. 4-5 , the flow meter assembly 10 can include one or more sensor assemblies 44 a, 44 b. The sensor assemblies 44 a, 44 b can be positioned within one or both of the cap chambers 36 a, 36 b and housing chambers 38 a, 38 b. In some embodiments, the sensor assemblies 44 a, 44 b are positioned outside of and on opposite sides of the measurement channel 40.

The sensor assemblies 44 a, 44 b can each include an outer cup portion 46 a, 46 b. The sensor assemblies 44 a, 44 b can each include a transducer assembly 54 a, 54 b. The transducer assembly 54 a, 54 b can be positioned at least partially within the outer cup portion 46 a, 46 b. The sensor assembly 44 a, 44 b can include a cap 56 a, 56 b configured to seal one side of the sensor assembly 44 a, 44 b and inhibit or prevent ingress of fluid into the sensor assemblies 44 a, 44 b from the interior of the flow meter assembly 10. The flow meter assembly can include one or more seals 45 (e.g., O-rings) positioned between the sensor assemblies, 44 a, 44 b and the caps 22 a, 22 b, and/or housing 26.

In some embodiments, as discussed in more detail below, the sensor assemblies 44 a, 44 b include an outlet port 60 a, 60 b configured to facilitate access of wires (not shown) or other components into the sensor assemblies 44 a, 44 b from outside of the flow meter assembly 10. As illustrated, the outlet ports 60 a, 60 b can be aligned with housing ports 62 a, 62 b which extend through the walls of the housing 26. Wires passed through the ports 60 a, 60 b, 62 a, 62 b can be connected to controllers, power sources, and/or other electrical components. Isolation of the wires from the fluid flowing through the meter assembly 10 can allow for flow measurements without concern for corrosion of the wires or other components within the sensor assemblies 44 a, 44 b. Such isolation can allow for flow rate measurement in corrosive chemicals and other fluids. One or more controllers (not shown) may be used to adjust components within the flow meter 10 in response to changes in fluid types, temperatures, and other factors.

As illustrated in FIGS. 7-8 , the outer cup portion 46 a, 46 b can include a head portion 48 a, 48 b. The outer cup portion 46 a, 46 b can include an elongate portion 52 a, 52 b. The elongate portion 52 a, 52 b can be connected to the head portion 48 a, 48 b and extend therefrom in a direction parallel to the channel axis 27. One or more flow channels 68 a, 68 b can be formed through the head portion 48 a, 48 b. The flow channels 68 a, 68 b can facilitate fluid flow past the sensor assemblies 44 a, 44 b through the flow meter assembly 10. The flow channels 68 a, 68 b can be bounded by boundary walls 66 a, 66 b. The boundary walls 66 a, 66 b can be curved form rounded ends to the flow channels 68 a, 68 b, as measured in a plane perpendicular to the channel axis.

The sensor assembly 44 a, 44 b can include a key feature 70 a, 70 b (e.g., a protrusion, indentation, or other keying feature). The key feature 70 a, 70 b can be configured to fit into or onto an alignment feature 72 a, 72 b (e.g., a protrusion, indentation, or other keying feature) of the housing 26. Interaction between the key feature 70 a, 70 b and alignment feature 72 a, 72 b can help to ensure proper alignment between the outlet ports 60 a, 60 b and the housing ports 62 a, 62 b. The head portion 48 a, 48 b can include one or more seal channels 77 configured to receive and/or align the seal(s) 45.

Referring to FIGS. 9-10 , the transducer assembly 54 a, 54 b can include an inner cup portion 76 a, 76 b. The inner cup portion 76 a, 76 b can be configured to house and/or receive a transducer 82 a, 82 b. In some embodiments, a transducer backing 83 a, 83 b can be positioned within the inner cup portion 76 a, 76 b behind the transducer 82 a, 82 b. In some embodiments, the backing 83 a, 83 b is an elastomer, epoxy, or other material configured to inhibit transmission of ultrasonic signals from the transducers 82 a, 82 b through the backing 83 a, 83 b.

As illustrated in FIG. 4 , the transducer 82 a, 82 b can have a width or diameter D7. The diameter D7 of the transducer can be greater than the diameter D6 of the measurement channel 40. For example, the diameter D6 of the transducer 82 a, 82 b can be at least 5% greater, at least 8% greater, at least 12% greater, at least 25% greater, at least 35% greater, at least 50% greater, and/or at least 100% greater than the diameter D6 of the measurement channel 40. In some embodiments, the diameter D7 of the transducer 82 a, 82 b is at least 0.1 inches, at least 0.2 inches, at least 0.25 inches, at least 0.3 inches, at least 0.4 inches, at least 0.75 inches, and/or at least 1 inch. For example, the diameter D7 of the transducer 82 a, 82 b can be approximately 0.375 inches.

Referring back to FIGS. 9-10 , the inner cup portion 76 a, 76 b can include a head portion 78 a, 78 b. The inner cup portion 76 a, 76 b can include an elongate portion 80 a, 80 b connected to and extending from the head portion 78 a, 78 b. The transducer 82 a, 82 b can be positioned within the elongate portion 80 a, 80 b at or near the end of the elongate portion 80 a, 80 b opposite the head portion 78 a, 78 b.

The head portion 78 a, 78 b of the inner cup portion 76 a, 76 b can be configured to engage with a portion of the elongate portion 52 a, 52 b. In some embodiments, the head portion 78 a, 78 b of the inner cup portion 76 a, 76 b is welded, adhered, or otherwise connected to the elongate portion 52 a, 52 b or some other portion of the sensor assembly 44 a, 44 b.

The elongate portion 52 a, 52 b can include a channel 84 a, 84 b. The channel 84 a, 84 b can extend through the entirety of the elongate portion 52 a, 52 b. In some embodiments, one end of the channel 84 a, 84 b is closed (e.g., the end facing the opposite sensor assembly 44 a, 44 b). The channel 84 a, 84 b can be sized and shaped to receive the elongate portion 80 a, 80 b of the inner cup portion 76 a, 76 b.

As illustrated in FIG. 11 , the elongate portion 52 a, 52 b can have a tapered end 86 a, 86 b (e.g., the end closest to the opposite sensor assembly 44 a, 44 b). In some embodiments, the elongate portion 52 a, 52 b has an overall “bullet” shape. When assembled, the transducer 82 a, 82 b can be positioned at or near the end of the elongate portion 52 a, 52 b (e.g., the tapered end) opposite the head 48 a, 48 b. In some embodiments, this end of the elongate portion 52 a, 52 b has the smallest diameter of any portion of the elongate portion 52 a, 52 b.

The transducer 82 a, 82 b can have an overall flat shape. For example, the transducer 82 a, 82 b can have a disc shape with a front side 88 a, 88 b and a back side 90 a, 90 b. The front side 88 a, 88 b of the transducer 82 a, 82 b can be the side facing the transducer 72 a, 72 b on the other end of the housing 26. The respective front sides 88 a, 88 b can be parallel to each other and can be positioned along the housing axis 27. Such alignment can facilitate successful transmission of ultrasonic signals between the two transducers 82 a, 82 b. In some embodiments, a wire conduit 92 a, 92 b is connected to the back side 90 a, 90 b of the transducer 82 a, 82 b. The wire conduit 92 a, 92 b can help guide electrical wires away from the transducer 82 a, 82 b and toward the outlet port 60 a, 60 b when the sensor assembly 44 a, 44 b is assembled.

The transducer 82 a, 872 b can be positioned along the housing axis 27. The width (e.g., diameter) of the transducer 82 a, 82 b can be greater than the diameter D6 of the measurement channel 40. The transducer 82 a, 82 b can be positioned behind a portion of the inner cup portion 76 a, 76 b through which the transducer 82 a, 82 b. For example, the inner cup portion 76 a, 76 b can include a wave guide portion 94 a, 94 b. The wave guide portion 94 a, 94 b can be on the end of the inner cup portion 76 a, 76 b closest the measurement channel 40. The wave guide portion 94 a, 94 b can have a wave guide face 96 a, 96 b facing toward the wave guide face 96 a, 96 b of the opposite sensor assembly 44 a, 44 b. The wave guide faces 96 a, 96 b can be flat and positioned along the housing axis to facilitate direction of the transducer signals parallel to the housing axis 27. The wave guide faces 96 a, 96 b can be parallel to each other. In some embodiments, the wave guide faces 96 a, 96 b have a concave configuration to focus the transducer signals inward toward the housing axis 27. In some embodiments, the wave guide 96 a, 96 b has a convex shape to direct the ultrasonic waves outward toward the walls of the measurement channel 40.

As illustrated in FIG. 5 , the wave guide faces 96 a, 96 b can be positioned close to the ends of the measurement channel 40 as measured parallel to the housing axis 27. In some embodiments, distance D8 between the wave guide faces 96 a, 96 b and the ends of the measurement channel 40 are less than 2 inches, less than 1.5 inches, less than 1 inch, less than 0.75 inches, less than 0.55 inches, less than 0.3 inches, and/or less than 0.1 inches, as measured parallel to the housing axis 27. In some embodiments, the distance D8 between the wave guide faces 96 a, 96 b and the measurement channel 40 is approximately 0.22 inches, as measured parallel to the housing axis 27. Maintaining a close distance between the wave guide faces 96 a, 96 b and the ends of the measurement channel 40 can increase the quality of the measurements obtainable by the transducers 82 a, 82 b. For example, maintaining a close distance can reduce the turbulence in the flow by maintaining a smooth flow path between the flow channels 68 a, 68 b and the measurement channel 40. This flow path can transition with relatively little or no diffusion from the flow channels 68 a, 68 b and the measurement channel 40. Reducing turbulence in the flow between the wave guide faces 96 a, 96 b and the measurement channel 40 can reduce the noise in the signal measured by the transducers 82 a, 82 b. In some embodiments, flow rates as low as 15 mL/min, as low as 10 mL/min, and/or as low as 5 mL/min can be measured.

The ratio between the distance D8 and the diameter D7 of the transducer 82 a, 82 b can be less than 2:1, less than 3:2, less than 4:3, less than 7:8, less than 3:4, less than 1:2, and/or less than 1:4. In some embodiments, the ratio between the distance D8 and the diameter D7 of the transducer 82 a, 82 b is approximately 3:5. The ratio between the distance D8 and the diameter D6 of the measurement channel 40 can be less than 2:1, less than 5:4, less than 6:5, less than 8:9, less than 1:2, less than 1:3, and/or less than 1:4. In some embodiments, the ratio between the distance D8 and the diameter D6 of the measurement channel 40 is approximately 9:10. Maintaining close ratios between the distance D8 and the diameters D6 and D7 can help to maintain a smooth flow at the entrance and exit of the measurement channel 40. Maintaining smooth flow (e.g., low turbulence) can reduce the noise in the signal measured by the transducers 82 a, 82 b and can allow for measurement of small flow rates.

Referring to FIG. 12 , the housing chamber 38 a, 38 b on either end of the housing 26 can have a tapered portion 98 a, 98 b. The tapered portion 98 a, 98 b can extend to the measurement channel 40.

Referring back to FIG. 5 , the flow meter assembly 10 can be symmetric about a plane (not shown) perpendicular to the housing axis 27 and positioned halfway along the length of the housing 26. Each of the cap apertures 32 a, 32 b, transducers 82 a, 82 b, and measurement channel 40 can be positioned along the housing axis 27 to facilitate a substantially straight fluid flow path through the flow meter assembly 10.

Either of the cap apertures 32 a, 32 b can function as an inlet to the flow meter assembly 10, while the opposite cap aperture 32 a, 32 b serves as the outlet to the flow meter assembly 10. For the purposes of discussion, the cap aperture 32 a on first end 14 will be referred to as the inlet, while the cap aperture 32 b on the second end 18 will be referred to as the outlet. Using inlets and outlets that are coaxial or otherwise aligned with the fluid flow path through the assembly 10 can reduce introduction of turbulence that would otherwise occur if lateral or oblique inlets/outlets were used.

Fluid (e.g., a liquid) that flows through the inlet 32 a passes into the cap chamber 36 a. The cap chamber 36 a can have filleted and/or chamfered internal surfaces to provide a smooth fluid flow surface. Providing a smooth flow surface can inhibit bubble generation within the fluid. The fluid in the cap chamber 36 a is directed through the flow channels 68 a of the sensor assembly 44 a into the housing chamber 38 a. The boundary walls 66 a can reduce turbulence and/or straighten the fluid flow through the system. For example, the boundary walls 66 a can inhibit vertical fluid flow through the channels 68 a. The flow stabilization provided by the boundary walls 66 a, 66 b can permit positioning of the flow meter assembly 10 closer to a bend in a piping system than may have been possible without the boundary walls 66 a, 66 b. The fluid then passes between the tapered end 86 a of the elongate portion 52 a and the tapered portion 98 a of the housing chamber 38 a. The fluid is accelerated into the measurement channel 40.

The flow rate of the fluid is measured by the transducers 82 a, 82 b as the fluid flows through the measurement channel 40. Each of the transducers 82 a, 82 b can send and receive ultrasonic signals when measuring flow rate through the measurement channel 40. The fluid then passes between the tapered end 86 b of the elongate portion 52 b and the tapered portion 98 b of the housing chamber 38 b. After passing through the housing chamber 38 b, the fluid is directed through the channels 68 b of the sensor assembly 44 b and into the cap chamber 36 b. The fluid then passes out through the outlet 32 b and into the pipe with which the cap 22 b is mated.

Utilizing a narrow measurement channel 40 (e.g., a channel narrower than the transducers 82 a, 82 b) can facilitate accurate and reliable measurement of very low liquid flow rates. For example, a flow meter assembly 10 as described in the present disclosure can measure flow rates as low as 15 mL/min, as low as 10 mL/min, and/or as low as 5 mL/min. Accurately measuring low flow rates such as those recited above can be especially beneficial in applications where chemicals or other components need to be added to another fluid at a reliably low level (e.g., due to safety considerations). This is often needed in small municipalities, individual homes, and other small scale water treatment and/or water deliver environments.

Another advantage provided by the flow meter assembly 10 is the ability to measure fluid velocity without needing to reflect ultrasonic signals off of the walls of the housing 26 or of any other component in the system. For example, flow meters which measure reflected signals must precisely align and position the transducers to ensure that the signals from each transducer will be received by the other transducer. Such alignment challenges in reflected-signal systems can be further exacerbated when the temperature and/or composition of the fluid changes, as these changes can require repositioning/realignment of one or both of the transducers. Further, imperfections, corrosion, sediment, and/or other abnormalities on the surface of the pipe walls can adversely affect the accuracy of reflected signals. Signal strength can also suffer when the ultrasonic signals are reflected due to phenomena such as dispersion of the signal and absorption of a portion of the signal by the reflecting surface. The above-recited challenges associated with reflected-signal systems can be avoided by the flow meter 10, as the ultrasonic signals generated by the transducers 82 a, 82 b are sent directly to the opposite transducer without reflection.

In some embodiments, one or more of the components within the caps 22 a, 22 b and/or housing 26 may be removed for cleaning, repair, or other maintenance. For example, one of the caps 22 a, 22 b may be disconnected from the housing 26, allowing a user access to the sensor assembly 44 a, 44 b.

FIGS. 13-21 illustrate an embodiment of a flow meter assembly 110. The flow meter assembly 110 includes some structures and functions that are the same as or similar to the structures and functions described above with respect to the flow meter assembly 10. Components of the flow meter 110 that are similar or the same in structure and/or function as the components of the flow meter 10 are labeled with a like reference number, wherein a value of “100” is added. For example, the wave guide faces 196 a, 196 b of the flow meter 110 are similar in structure and function as the wave guide faces 96 a, 96 b of the flow meter 10. Unless otherwise noted below, the like components of the flow meter 110 are the same as or similar in structure and/or function as the like elements of the flow meter 10.

As illustrated in FIGS. 13-15 , the flow meter assembly 110 can include a plurality of housing components. For example, the flow meter assembly 110 can include a first housing portion 126 a, and a second housing portion 126 b. The first and second housing portions 126 a, 126 b can be similar in structure to each other and can be mirrored about the longitudinal axis of the assembly 110. In some embodiments, one or both of the first and second housing portions 126 a, 126 b can include apertures 135 though which fasteners 131 or other components can be inserted. The fasteners 131 (FIG. 16 ) can be configured to hold the first and second housing portions 126 a, 126 b together when assembled.

The flow meter assembly 110 can include a third or inner housing portion 126 c. The third housing portion 126 c can be positioned at least partially between the first and second housing portions 126 a, 126 b. In some embodiments, a housing interior 123 (FIG. 17 ) is formed between the third housing portion 126 c and the first and second housing portions 126 a, 126 b. The fasteners 131 can be configured to pass through at least a portion of the third housing 126 c to secure the third housing 126 c to and/or between the

As illustrated in FIG. 16 , the assembly 110 can include one or more seals 127 a, 127 b. The seals 127 a, 127 b can be positioned between two or more of the housing portions 126 a, 126 b, 126 c (collectively “126”) to seal the housing interior 123. In some embodiments, the seals 127 a, 127 b are shaped and sized to match one or more surfaces of the housing portions 126. The seals 127 a, 127 b can be configured to seal the interface between the third housing portion 126 c and the first housing portion 126 a, and the interface between the third housing portion 126 c and the second housing portion 126 b, respectively.

One or more electrical components (e.g., circuit boards, controllers, wireless or wired transmitters, batteries, sensors, memory units, processors, etc.) can be positioned at least partially within the housing interior 123. As illustrated, electrical components 143, 145 can be positioned on one or both sides of the third housing portions 126 c. Grommets 129 or other sealing structures can be used to facilitate passage of wires and/or cables from an exterior of the housing portions 126 to the housing interior 123. In some embodiments, the assembly 110 is completely wireless and without holes or other access structures into the housing interior 123 when the assembly 110 is assembled.

In some embodiments, two or more components of the assembly 110 are connected to each other via spin welding. For example, the caps 122 a, 122 b can be spin welded to the outer cup portions 146 a, 146 b of the sensor assemblies 144 a, 144 b. In some embodiments, the outer cup portions 146 a, 146 b are spin welded to the third housing 126 c. Spin welding the components to each other can realize a number of benefits. For example, the spin welding process can create a chemical bond between the welded components that can reduce or eliminate the need for using separate O-rings or other sealing structures. This can increase the life of the assembly 110 and reduce the need to replace the seals over time. In some configurations, as illustrated in FIG. 17 , the voids 167 are formed in various portions of the assembly 110 to capture material (e.g., flakes, chips, or other material) generated during the spin welding process.

Preferably, the various marked distances and diameters in FIG. 17 are the same as or similar to the distances and diameters described above with respect to FIGS. 4 and 5 . For example, widths/diameters D13, D14, D15, D16, and D17 can be the same as or similar to the widths/diameters D3, D4, D5, D6, and D7, respectively. The distance D18 can be the same as or similar to the distance D8. As illustrated in FIG. 17 , the wave guide faces 196 a, 196 b can extend beyond the inner cup portions 176 a, 176, respectively, in a direction toward the measurement channel 40. This extension can create a step between the wave guide faces 196 a, 196 b and the inner cup portions 176 a, 176 to inhibit or prevent formation of bubbles on wave guide faces 196 a, 196 b. The respective ratios between the distances and widths/diameters in the assembly 110 can be the same as or similar to those distances and widths/diameters described above with respect to assembly 10.

As illustrated in FIGS. 17 and 18 , the inner walls of the housing chambers 138 a, 138 b can have the same or similar slopes/tapers as the elongate portions 152 a, 152 b of the outer cup portions 146 a, 146 b. Utilizing similar shapes, curves, and/or tapers between the inner walls of the housing chambers and the outer walls of the elongate portions can reduce turbulence in the flow of fluid through the system, as instances of nuzzling and diffusing can be reduced.

As illustrated in FIGS. 16-21 , the outer cup portions 146 a, 146 b and third housing 126 c can include one or more ports or channels through which wires or cables can be inserted into an interior of the elongate portions 152 a, 152 b of the outer cup portions 146 a, 146 b. As illustrated in FIG. 21 , outlet channels 160 a, 160 b can extend through the boundary walls 166 a, 166 b of the outer cup portion 146 a, 146 b. The outlet channels 160 a, 160 b can have inner ports 163 a, 163 b and outer ports 165 a, 165 b. The outlet channels 160 a, 160 b can be aligned with housing ports 162 a, 162 b to facilitate passage of wires (e.g., the wires 169 a, 169 b of FIG. 17 ) into the interiors of the elongate portions 152 a, 152 b.

The terms “approximately”, “about”, “generally” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of the stated amount.

While the preferred embodiments of the present inventions have been described above, it should be understood that they have been presented by way of example only, and not of limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the inventions. Thus the present inventions should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents. Furthermore, while certain advantages of the inventions have been described herein, it is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the inventions. Thus, for example, those skilled in the art will recognize that the inventions may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 

What is claimed is:
 1. A flow rate assembly comprising: a housing having: a housing axis; a first end having an inlet positioned along the housing axis; a second end having an outlet positioned along the housing axis; and a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis; a first outer cup portion positioned at least partly within the housing, the first outer cup portion comprising: a head portion connected to a wall of the housing; an elongate portion connected to the head portion, the elongate portion having a first face facing the measurement channel; and a plurality of flow channels through the head portion configured to permit fluid to flow past the first outer cup portion through the plurality of flow channels, each of the plurality of flow channels of the first outer cup portion having an end facing an end of another of the plurality of flow channels, so that a boundary wall is formed between facing ends, each boundary wall positioned symmetrical to another boundary wall relative to the housing axis; and a first transducer positioned along the housing axis and within the elongate portion, the first transducer sealed from fluid flow past the first outer cup portion, the first transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the first transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel; wherein the first and second ends of the housing are configured to mate with an open pipe end in an in-line manner.
 2. The flow rate assembly of claim 1, comprising: a second outer cup portion positioned at least partially within the housing, the second outer cup portion comprising: an outer head portion connected to a wall of the housing: an elongate portion connected to the outer head portion; and a plurality of flow channels through the outer head portion configured to permit fluid to flow past the second outer cup portion through the plurality of flow channels, each of the plurality of flow channels of the second outer cup portion having an end facing an end of another of the plurality of flow channels, so that a boundary wall is formed between facing ends, each boundary wall positioned symmetrical to another boundary wall relative to the housing axis; and a second transducer positioned within the elongate portion of the second outer cup portion and sealed from fluid flow past the second outer cup portion, the second transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel; wherein the second transducer is configured generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel toward the first transducer.
 3. The flow rate assembly of claim 1, wherein the first outer cup portion includes an outlet channel extending between an interior of the elongate portion and an exterior of the elongate portion.
 4. The flow rate assembly of claim 3, wherein the outlet channel extends through at least one boundary wall.
 5. The flow rate assembly of claim 1, wherein the housing comprises a first housing portion, a second housing portion, and third housing portion positioned between the first and second housing portions, wherein the measurement channel extends through the third housing portion.
 6. The flow rate assembly of claim 5, wherein one or more electrical components are positioned within a space between the third housing portion and the first housing portion.
 7. A flow rate assembly comprising: a housing having: a housing axis; a first end having an inlet positioned along the housing axis; a second end having an outlet positioned along the housing axis; a measurement channel extending along the housing axis and through a portion of the housing between the first and second ends of the housing, the measurement channel having a width perpendicular to the housing axis; and a first housing chamber between the measurement channel and the inlet, as measured along the housing axis, the first housing chamber having a tapered inner wall; a first outer cup portion positioned at least partly within the first housing chamber, the first outer cup portion comprising: a head portion connected to a wall of the housing; an elongate portion connected to the head portion, the elongate portion having a tapered portion between a first face and the inlet and the measurement channel; and at least one flow channel through the head portion configured to permit fluid to flow past the first outer cup portion through the at least one flow channel; and a transducer positioned along the housing axis and within the elongate portion, the transducer sealed from fluid flow past the first outer cup portion, the transducer having a width perpendicular to the housing axis and greater than the width of the measurement channel, the transducer configured to generate an ultrasonic signal and to direct the ultrasonic signal through the measurement channel; wherein the housing comprises a first housing, a second housing, and a third housing, the third housing positioned between the first housing and the second housing, the flow rate assembly comprising at least one circuit board mounted within a housing interior formed between the first housing and the third housing.
 8. The flow rate assembly of claim 7, wherein the head portion of the first outer cup portion forms a port for receiving a wire which communicates with the housing interior formed between the first housing and the third housing.
 9. The flow rate assembly of claim 7, comprising an electrical component mounted within a housing interior formed between the second housing and the third housing.
 10. The flow rate assembly of claim 9, comprising a cap positioned at the first end of the housing and forming the inlet, wherein the cap is configured to engage with an open fluid conduit and the cap is spin welded to the first outer cup portion.
 11. The flow rate assembly of claim 7, wherein the head portion of the first outer cup portion forms a port for receiving a wire which communicates with the housing interior formed between the first housing and the third housing and the transducer is fluidly isolated from fluid flowing through the assembly.
 12. The flow rate assembly of claim 7, comprising an inner cup portion positioned at least partially within the elongate portion of the first outer cup portion, wherein the transducer is positioned within the inner cup portion and wherein a connection between the inner cup portion and the first outer cup portion forms a seal to inhibit or prevent fluid ingress into the elongate portion of the first outer cup portion.
 13. The flow rate assembly of claim 12, wherein the inner cup portion has a flat face facing the measurement channel. 